Association of Body Mass Index and Cardiometabolic Factors With Elderly Suicide: A Cohort Study of 101,518 Older Taiwanese

Background: Older people have the highest suicide rate across age groups in most countries. The prevalence of cardiometabolic risk factors also increases with age. We investigated the association between body mass index (BMI), cardiometabolic risk factors, and suicide in a large cohort of older people in Taiwan. Methods: We conducted a cohort study using data from an elderly health examination program in Taipei City, Taiwan (2005-2010), linked to the national cause-of-death data files. We used competing risk Cox regression models to investigate the associations of BMI (kg/m²) and cardiometabolic factors with suicide after adjusting for sex, age, socioeconomic variables, chronic diseases, psychological distress, and cognitive function. Results: Among 101,518 individuals aged ≥ 65 years, 92 died by suicide during an average follow-up of 3.9 years. Underweight (BMI<18.5) was associated with increased suicide risk (adjusted hazard ratio [aHR]=2.33, 95% confidence interval [CI] 1.20-4.52) (reference: normal weight). Low diastolic blood pressure was associated with increased suicide risk – aHR was 0.51 (95% CI 0.29-0.91) and 0.55 (95% CI 0.31-0.99) for the third and fourth quartiles of diastolic blood pressure (reference: the lowest quartile), respectively. Older people with a higher waist circumference (aHR per 1-standard-deviation increase=0.60 [95% CI 0.37-0.98]) and a higher number of metabolic syndrome criteria (aHR per 1-criterion increase=0.65 [95% 0.46-0.92]) had lower suicide risk. Systolic blood pressure, pulse rate, fasting blood glucose, and lipid profiles were not associated with suicide risk. Conclusions: Underweight, low diastolic blood pressure, and low waist circumference may be markers of increased suicide risk in older people.